Generator systems such as those used in aircraft engine applications, for example, require output voltage self-build-up charcteristics. Such systems may be incorporated in auxiliary generators for aircraft accessories or in integrated drive generators. Conventionally, such generator systems may be of a conventional brush type or may be brushless machines. Brush type DC machines do not use output rectifiers to obtain DC voltage because commutator action provides this function.
Most such generator systems include a main stator and rotating field "set" associated with a rotor shaft. A separate exciter field and exciter armature "set" also is operatively associated with the rotor shaft separate from the main stator and rotating field set. A completely separate permanent magnet generator, including permanent magnets and a stator, also is operatively associated with the rotor shaft. Examples of such generator systems utilizing three distinct "sets" are shown in U.S. Pat. Nos. 3,260,872 to Potter, dated Apr. 13, 1964; 4,223,263 to Hansen, Jr. et al, dated Sept. 16, 1980 and 4,514,652 to Olson, dated Apr. 30, 1985, the Olson patent being assigned to the assignee of this invention.
As is known and can be derived from the aforesaid patents, the permanent magnet generator provides sufficient induced current to create a magnetic field in the exciter of the generator system. This, in turn, causes generation of current in the exciter rotor windings, usually as alternating current, which then is rectified to energize the main rotor windings which, in turn, causes the induction of current within the main stator windings which is employed as desired, such as for aircraft accessories.
This invention is directed to a new and improved generator system of the character described wherein a permanent magnet generator is incorporated integral with the exciter set.